BOSTON (AP) — About 300 to 500 defendants, including some “pretty dangerous people,” may be released into Boston streets because of the alleged mishandling of evidence at a Massachusetts drug lab, a prosecutor said Friday.

Chemist Annie Dookhan is charged with obstruction of justice for allegedly skirting protocols and faking test results at the now-closed state drug lab. At least two dozen defendants whose cases Dookhan handled have been released, including career criminal and convicted rapist Marcus Pixley.

Pixley was released on bail earlier this month but failed to show up for court Wednesday. Quincy police arrested him Friday; a judge doubled his bail to $2,000 and set his next court date for Oct. 15.

Suffolk District Attorney Dan Conley said officials in Boston are “concerned that there may be violence” if other defendants and convicts are released and have discussed intervening in the lives of those who are freed in order to prevent repeat offenses.

“We may be in the position, we undoubtedly will be in the position, to assent to the release of some pretty dangerous people into Boston,” Conley said.

Meanwhile, Mayor Thomas Menino said federal officials should offer support to ensure that those released are monitored so “they’re not back out on the streets doing the same thing they did in the past.”

“Our crime rate in Boston right now is down, but if we’re going to have maybe 1,200 individuals released to the streets of our city, what will happen in the future?” Menino asked reporters during a campaign stop for U.S. Senate candidate Elizabeth Warren. “It’s an emergency.”

On Friday, Boston Municipal Court held the first special session to handle criminal cases challenged in light of the lab scandal.

Defendants Carlos Colon and Michael Wells were released because Dookhan signed off on or tested their samples.

Wells, 24, was arrested in 2009, then violated his probation with drug distribution charges in 2011. Dookhan tested the 2011 sample, and Wells has since been in jail.

Saunders said Wells was accepted to Le Cordon Bleu culinary school and has a young daughter and fiancee. He was released on personal recognizance and must adhere to a curfew.

Colon, 21, who had a drug distribution conviction in 2011, was released on $500 bail and a curfew.

Three other defendants with cases related to Dookhan were not released while attorneys continue gathering information or because they are serving time for other sentences.

Of the 18 cases heard Friday, only five actually involved Dookhan.

Conley said court officials “hastily” compiled the list of defendants brought in for hearings without input from prosecutors or defense attorneys.

“What is going on here today is taking away from our real work that we have to do to identify who really was affected,” Conley said during a break.

Most defendants were in custody at South Bay House of Correction and brought into court one by one when their names were called.

“You have these poor folks, they did their time, they’re doing their time, they admitted to what they’ve done, and they have to be traipsed in here in handcuffs and prison garb ... all of these not related to Annie Dookhan,” Conley said. “I think this court also has to be embarrassed.”

Asked about public safety in light of the release of inmates, Gov. Patrick Deval said freeing them is not a “technicality.”

“We are talking about people who shouldn’t have been convicted and who need to have justice done in their cases,” he said.

“In terms of people who have other charges or records, there’s a process for that, there’s a system for that and there’s public safety officials who have responsibility for that,” he added.

Deval said it was too early to estimate how much the state would spend to address the crisis.